I. Field of the Invention
The present invention relates to electronic animal confinement systems and, more specifically, to such systems in which a receiver on the animal responds to an electronic signal to alert the animal to stay behind a boundary that is electronically defined by the signal.
II. Description of Prior Art
Electronic animal confinement systems have become very popular because they use electronic signals to create a boundary rather than an unsightly fence. For example, a boundary signal emitter wire is buried around the perimeter of the yard in which a pet, such as a dog, is to be confined. A transmitter hidden in the house or garage is electrically connected directly to the emitter to energize the wire with an RF boundary signal generated in the transmitter. The wire radiates the RF signal to thus electronically define an imaginary "boundary" coincident with the wire. A receiver worn about the neck of the dog and responsive to the radiated RF signal will sense or respond to the boundary signal as the dog approaches the boundary (e.g., the wire). The receiver includes circuitry designed to provide a shock to the dog to cause the dog to move away from the boundary. As a result, the dog may be kept in the yard without an unsightly fence.
Unfortunately, such systems are not without drawbacks. For example, in some situations, the receiver might not actually pick up the boundary signal as the pet approaches the boundary allowing the dog to simply "run through" the boundary. Similarly, if the dog is trapped near the boundary, repeated shocks will be administered for as long as the battery has power. Such long-term exposure to shocks is painful and deleterious to the animal. In other situations, non-boundary RF signals, such as from AC motors, electric utility cables, television sets, or the like, could be picked up by the receiver causing the dog to receive an unexpected and undesired shock even though the pet may not be near the boundary. Other problems have been experienced which further limit the utility of such animal confinement systems.
In a storm, for example, the wire acts not only as an emitter of the RF boundary signal, but may also attract energy such as from lightning. Should lightning strike at or near the wire, the transmitter circuitry may be damaged or destroyed. Also, the receiver units worn by the pet are battery-powered. It is not uncommon for the receiver to drain the battery fairly quickly. As a result, there is the risk of failure of the system to keep the pet confined due to battery failure, as well as the annoyance of frequent battery replacement to avoid such failure. An additional problem with typical receivers is that the metal lugs extending from the receiver and into the pet's neck to shock the dog are very hard and may tend to scratch or irritate the dog's neck.